Methods for evaluating the integrity of a uterine cavity

ABSTRACT

Methods, systems and devices for evaluating the integrity of a uterine cavity. A method comprises introducing transcervically a probe into a patient&#39;s uterine cavity, providing a flow of a fluid (e.g., CO 2 ) through the probe into the uterine cavity and monitoring the rate of the flow to characterize the uterine cavity as perforated or non-perforated based on a change in the flow rate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/488,214, filed Jun. 4, 2012, now U.S. Pat. No. 9,883,907, which is acontinuation of U.S. patent application Ser. No. 13/442,449, filed Apr.9, 2012, now U.S. Pat. No. 9,788,890, which claims the benefit of U.S.Provisional Patent Application No. 61/483,542, filed May 6, 2011; andU.S. Provisional Patent Application No. 61/491,842, filed May 31, 2011,the entire contents of which are incorporated herein by reference intheir entirety.

BACKGROUND 1. Field of the Invention

The present invention relates to electrosurgical methods and devices forglobal endometrial ablation in a treatment of menorrhagia. Moreparticularly, the present invention relates to applying radiofrequencycurrent to endometrial tissue by means of capacitively coupling thecurrent through an expandable, thin-wall dielectric member enclosing anionized gas.

A variety of devices have been developed or proposed for endometrialablation. Of relevance to the present invention, a variety ofradiofrequency ablation devices have been proposed including solidelectrodes, balloon electrodes, metalized fabric electrodes, and thelike. While often effective, many of the prior electrode designs havesuffered from one or more deficiencies, such as relatively slowtreatment times, incomplete treatments, non-uniform ablation depths, andrisk of injury to adjacent organs.

For these reasons, it would be desirable to provide systems and methodsthat allow for endometrial ablation using radiofrequency current whichis rapid, provides for controlled ablation depth and which reduce therisk of injury to adjacent organs. At least some of these objectiveswill be met by the invention described herein.

2. Description of the Background Art

U.S. Pat. Nos. 5,769,880; 6,296,639; 6,663,626; and 6,813,520 describeintrauterine ablation devices formed from a permeable mesh definingelectrodes for the application of radiofrequency energy to ablateuterine tissue. U.S. Pat. No. 4,979,948 describes a balloon filled withan electrolyte solution for applying radiofrequency current to a mucosallayer via capacitive coupling. US 2008/097425, having commoninventorship with the present application, describes delivering apressurized flow of a liquid medium which carries a radiofrequencycurrent to tissue, where the liquid is ignited into a plasma as itpasses through flow orifices. U.S. Pat. No. 5,891,134 describes aradiofrequency heater within an enclosed balloon. U.S. Pat. No.6,041,260 describes radiofrequency electrodes distributed over theexterior surface of a balloon which is inflated in a body cavity to betreated. U.S. Pat. No. 7,371,231 and US 2009/054892 describe aconductive balloon having an exterior surface which acts as an electrodefor performing endometrial ablation. U.S. Pat. No. 5,191,883 describesbipolar heating of a medium within a balloon for thermal ablation. U.S.Pat. Nos. 6,736,811 and 5,925,038 show an inflatable conductiveelectrode.

BRIEF SUMMARY

The following presents a simplified summary of some embodiments of theinvention in order to provide a basic understanding of the invention.This summary is not an extensive overview of the invention. It is notintended to identify key/critical elements of the invention or todelineate the scope of the invention. Its sole purpose is to presentsome embodiments of the invention in a simplified form as a prelude tothe more detailed description that is presented later.

The present invention provides methods, systems and devices forevaluating the integrity of a uterine cavity. The uterine cavity may beperforated or otherwise damaged by the transcervical introduction ofprobes and instruments into the uterine cavity. If the uterine wall isperforated, it would be preferable to defer any ablation treatment untilthe uterine wall is healed.

A method of the invention comprises introducing transcervically a probeinto a patient's uterine cavity, providing a flow of a fluid (e.g., CO₂)through the probe into the uterine cavity and monitoring the rate of theflow to characterize the uterine cavity as perforated or non-perforatedbased on a change in the flow rate. If the flow rate into the cavitydrops to zero or close to zero within a predetermined time period, thisindicates that the uterine cavity is intact and not perforated. If theflow rate does not drop to zero or close to zero, this indicates that afluid flow is leaking through a perforation in the uterine cavity intothe uterine cavity or escaping around an occlusion balloon that occludesthe cervical canal.

Embodiments herein provide a method of characterizing a patient'suterus, comprising introducing a flow of a fluid into a uterine cavityof a patient; and monitoring the flow to characterize the uterine cavityas at least one of perforated or non-perforated based on a change in arate of the flow. Introducing may be, for example, transcervicallyintroducing a probe into the uterine cavity, and introducing the flowthrough the probe.

Monitoring may include providing a signal, responsive to the rate offlow, that characterizes the uterine cavity as at least one ofperforated or non-perforated. As an example, monitoring may includegenerating a signal responsive to the rate of flow not dropping below apredetermined level, the signal characterizing the uterine cavity asperforated. In embodiments, the predetermined level is 0.05 slpm.

In embodiments, monitoring comprises generating a signal responsive tothe rate of flow dropping below a predetermined level, the signalcharacterizing the uterine cavity as non-perforated. The predeterminedlevel may be, for example, 0.05 slpm.

In further embodiments, monitoring comprises monitoring a rate of flowafter a predetermined first interval after initiation of the flow. Thefirst interval may be, as examples, at least 5 seconds, at least 15seconds, or at least 30 seconds.

Monitoring may additionally include monitoring a rate of flow over asecond predetermined interval after the first interval. The secondinterval may be a least 1 second, at least 5 seconds, or at least 10seconds, as examples.

In additional embodiments, monitoring includes providing a signal,responsive to the rate of flow, that characterizes the uterine cavity asat least one of perforated or non-perforated, and wherein the signal isat least one of visual, aural and tactile.

In embodiments, prior to introducing the flow, a member is positionedwithin the cervical canal that substantially prevents a flow of thefluid out of the uterine cavity. Introducing may include transcervicallyintroducing a probe into the uterine cavity, and introducing the flowthrough the probe, with the member positioned about an exterior of theprobe. The member may be expanded in the cervical canal.

In embodiments, the fluid is a gas or a liquid.

In additional embodiments, introducing includes transcervicallyintroducing a probe into the uterine cavity, and introducing the flowthrough the probe. The probe has a working end with an energy-deliverysurface for ablating uterine cavity tissue. Responsive to the uterinecavity being characterized as perforated, energy delivery surface isdisabled. Alternatively or additionally, responsive to the uterinecavity being characterized as non perforated, activation of the energydelivery surface may be enabled or even caused to happen automatically.

In embodiments, a method of endometrial ablation is provided, the methodincluding introducing an ablation probe into a uterine cavity of apatient; flowing a fluid from a fluid source through the probe into theuterine cavity; monitoring the rate of the flow of the fluid into theuterine cavity to characterize the cavity as at least one of perforatedor non-perforated based on a change in the flow rate; and responsive theto the uterine cavity being characterized as non perforated, activatingthe ablation probe to ablate an interior of the uterine cavity.

For a fuller understanding of the nature and advantages of the presentinvention, reference should be made to the ensuing detailed descriptionand accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to better understand the invention and to see how it may becarried out in practice, some preferred embodiments are next described,by way of non-limiting examples only, with reference to the accompanyingdrawings, in which like reference characters denote correspondingfeatures consistently throughout similar embodiments in the attacheddrawings.

FIG. 1 is a perspective view of an ablation system corresponding to theinvention, including a hand-held electrosurgical device for endometrialablation, RF power source, gas source and controller.

FIG. 2 is a view of the hand-held electrosurgical device of FIG. 1 witha deployed, expanded thin-wall dielectric structure.

FIG. 3 is a block diagram of components of one electrosurgical systemcorresponding to the invention.

FIG. 4 is a block diagram of the gas flow components of theelectrosurgical system of FIG. 1.

FIG. 5 is an enlarged perspective view of the expanded thin-walldielectric structure, showing an expandable-collapsible frame with thethin dielectric wall in phantom view.

FIG. 6 is a partial sectional view of the expanded thin-wall dielectricstructure of FIG. 5 showing (i) translatable members of theexpandable-collapsible frame a that move the structure between collapsedand (ii) gas inflow and outflow lumens.

FIG. 7 is a sectional view of an introducer sleeve showing variouslumens of the introducer sleeve taken along line 7-7 of FIG. 6.

FIG. 8A is an enlarged schematic view of an aspect of a method of theinvention illustrating the step introducing an introducer sleeve into apatient's uterus.

FIG. 8B is a schematic view of a subsequent step of retracting theintroducer sleeve to expose a collapsed thin-wall dielectric structureand internal frame in the uterine cavity.

FIG. 8C is a schematic view of subsequent steps of the method,including, (i) actuating the internal frame to move the a collapsedthin-wall dielectric structure to an expanded configuration, (ii)inflating a cervical-sealing balloon carried on the introducer sleeve,and (iii) actuating gas flows and applying RF energy tocontemporaneously ionize the gas in the interior chamber and causecapacitive coupling of current through the thin-wall dielectricstructure to cause ohmic heating in the engaged tissue indicated bycurrent flow paths.

FIG. 8D is a schematic view of a subsequent steps of the method,including: (i) advancing the introducer sleeve over the thin-walldielectric structure to collapse it into an interior bore shown inphantom view, and (ii) withdrawing the introducer sleeve and dielectricstructure from the uterine cavity.

FIG. 9 is a cut-away perspective view of an alternative expandedthin-wall dielectric structure similar to that of FIGS. 5 and 6 show analternative electrode configuration.

FIG. 10 is an enlarged cut-away view of a portion of the expandedthin-wall dielectric structure of FIG. 9 showing the electrodeconfiguration.

FIG. 11 is a schematic view of a patient uterus depicting a methodcorresponding to the invention including providing a flow of a fluidmedia into the uterine cavity and monitoring the flow rate tocharacterize the patient's uterine cavity as intact and non-perforated.

FIG. 12 is a perspective view of the ablation device of FIGS. 1-2 with asubsystem for checking the integrity of a uterine cavity.

FIG. 13 represents a block diagram of a subsystem of the invention forproviding and monitoring a fluid flow into the patient's uterine cavity.

FIG. 14 represents a diagram indicating the steps of an algorithm forproviding and monitoring a fluid flow into the patient's uterine cavity.

FIG. 15 is a chart illustrating gas flow rates into the uterine cavityover time that will result in three conditions to thereby characterizethe uterine cavity as non-perorated or perforated.

FIG. 16 represents a diagram indicating the steps of an algorithm forproviding and monitoring a fluid flow related to the test method of FIG.15.

FIG. 17 is a schematic view of another system and method for providingand monitoring a fluid flow to characterize the integrity of a uterinecavity.

FIG. 18A is a schematic view of system with an expandable working endproperly deployed in the uterine cavity, and illustrates a variation ofa method for characterizing the integrity of a uterine cavity, wherein afirst stage of a two-stage test which monitors CO₂ flows into theuterine cavity exterior of the working end or dielectric structure.

FIG. 18B illustrates the second stage of the two-stage test whichmonitors CO₂ flows in the uterine cavity exterior of the dielectricstructure in response to Argon gas flows into the interior chamber ofthe dielectric structure.

FIG. 19 is a box diagram illustrating the steps of a second stage testas illustrated in FIG. 18B.

FIG. 20A is a schematic view of an expandable working end that is notdeployed in the uterine cavity and positioned in a uterine wallperforation, and illustrates a first stage of a two-stage test whichmonitors CO₂ flows into the uterine cavity exterior of the working end.

FIG. 20B illustrates the second stage of the two-stage test whichmonitors CO₂ flows in the uterine cavity exterior of the dielectricstructure in response to Argon gas flows into the interior chamber ofthe dielectric structure.

FIG. 21 is a box diagram illustrating the steps of a variation of thesecond stage of a two stage test.

FIG. 22A is a schematic view of an expandable dielectric deployed in theuterine cavity and illustrates a test in which the dielectric issuctioned against an interior frame by a negative pressure source.

FIG. 22B is a schematic view of the expandable dielectric of FIG. 22Aimproperly deployed in a perforated wall of a uterine cavity andillustrates the test wherein the dielectric is suctioned against theinterior frame by the negative pressure source.

FIG. 23 is an expanded schematic view of the expandable dielectric inthe uterine wall perforation illustrating the escape of CO₂ gas and testfailure mode.

FIG. 24 is a chart illustrating a combination two-stage cavity integritytest wherein the first stage comprises the test described in FIGS. 15-16and the second stage comprises the test described in FIGS. 22A-23.

DETAILED DESCRIPTION

In the following description, various embodiments of the presentinvention will be described. For purposes of explanation, specificconfigurations and details are set forth in order to provide a thoroughunderstanding of the embodiments. However, it will also be apparent toone skilled in the art that the present invention may be practicedwithout the specific details. Furthermore, well-known features may beomitted or simplified in order not to obscure the embodiment beingdescribed.

In general, an electrosurgical ablation system is described herein thatcomprises an elongated introducer member for accessing a patient'suterine cavity with a working end that deploys an expandable thin-walldielectric structure containing an electrically non-conductive gas as adielectric. In one embodiment, an interior chamber of the thin-walldielectric structure contains a circulating neutral gas such as argon.An RF power source provides current that is coupled to the neutral gasflow by a first polarity electrode disposed within the interior chamberand a second polarity electrode at an exterior of the working end. Thegas flow, which is converted to a conductive plasma by an electrodearrangement, functions as a switching mechanism that permits currentflow to engaged endometrial tissue only when the voltage across thecombination of the gas, the thin-wall dielectric structure and theengaged tissue reaches a threshold that causes capacitive couplingacross the thin-wall dielectric material. By capacitively couplingcurrent to tissue in this manner, the system provides a substantiallyuniform tissue effect within all tissue in contact with the expandeddielectric structure. Further, the invention allows the neutral gas tobe created contemporaneously with the capacitive coupling of current totissue.

In general, this disclosure may use the terms “plasma”, “conductive gas”and “ionized gas” interchangeably. A plasma consists of a state ofmatter in which electrons in a neutral gas are stripped or “ionized”from their molecules or atoms. Such plasmas can be formed by applicationof an electric field or by high temperatures. In a neutral gas,electrical conductivity is non-existent or very low. Neutral gases actas a dielectric or insulator until the electric field reaches abreakdown value, freeing the electrons from the atoms in an avalancheprocess thus forming a plasma. Such a plasma provides mobile electronsand positive ions, and acts as a conductor which supports electriccurrents and can form spark or arc. Due to their lower mass, theelectrons in a plasma accelerate more quickly in response to an electricfield than the heavier positive ions, and hence carry the bulk of thecurrent.

FIG. 1 depicts one embodiment of an electrosurgical ablation system 100configured for endometrial ablation. The system 100 includes a hand-heldapparatus 105 with a proximal handle 106 shaped for grasping with ahuman hand that is coupled to an elongated introducer sleeve 110 havingaxis 111 that extends to a distal end 112. The introducer sleeve 110 canbe fabricated of a thin-wall plastic, composite, ceramic or metal in around or oval cross-section having a diameter or major axis ranging fromabout 4 mm to 8 mm in at least a distal portion of the sleeve thataccesses the uterine cavity. The handle 106 is fabricated of anelectrically insulative material such as a molded plastic with apistol-grip having first and second portions, 114 a and 114 b, that canbe squeezed toward one another to translate an elongated translatablesleeve 115 which is housed in a bore 120 in the elongated introducersleeve 110. By actuating the first and second handle portions, 114 a and114 b, a working end 122 can be deployed from a first retracted position(FIG. 1) in the distal portion of bore 120 in introducer sleeve 110 toan extended position as shown in FIG. 2. In FIG. 2, it can be seen thatthe first and second handle portions, 114 a and 114 b, are in a secondactuated position with the working end 122 deployed from the bore 120 inintroducer sleeve 110.

FIGS. 2 and 3 shows that ablation system 100 includes an RF energysource 130A and RF controller 130B in a control unit 135. The RF energysource 130A is connected to the hand-held device 105 by a flexibleconduit 136 with a plug-in connector 137 configured with a gas inflowchannel, a gas outflow channel, and first and second electrical leadsfor connecting to receiving connector 138 in the control unit 135. Thecontrol unit 135, as will be described further below in FIGS. 3 and 4,further comprises a neutral gas inflow source 140A, gas flow controller140B and optional vacuum or negative pressure source 145 to providecontrolled gas inflows and gas outflows to and from the working end 122.The control unit 135 further includes a balloon inflation source 148 forinflating an expandable sealing balloon 225 carried on introducer sleeve110 as described further below.

Referring to FIG. 2, the working end 122 includes a flexible, thin-wallmember or structure 150 of a dielectric material that when expanded hasa triangular shape configured for contacting the patient's endometriallining that is targeted for ablation. In one embodiment as shown inFIGS. 2, 5 and 6, the dielectric structure 150 comprises a thin-wallmaterial such as silicone with a fluid-tight interior chamber 152.

In an embodiment, an expandable-collapsible frame assembly 155 isdisposed in the interior chamber. Alternatively, the dielectricstructure may be expanded by a neutral gas without a frame, but using aframe offers a number of advantages. First, the uterine cavity isflattened with the opposing walls in contact with one another. Expandinga balloon-type member may cause undesirable pain or spasms. For thisreason, a flat structure that is expanded by a frame is better suitedfor deployment in the uterine cavity. Second, in embodiments herein, theneutral gas is converted to a conductive plasma at a very low pressurecontrolled by gas inflows and gas outflows—so that any pressurization ofa balloon-type member with the neutral gas may exceed a desired pressurerange and would require complex controls of gas inflows and gasoutflows. Third, as described below, the frame provides an electrode forcontact with the neutral gas in the interior chamber 152 of thedielectric structure 150, and the frame 155 extends into all regions ofthe interior chamber to insure electrode exposure to all regions of theneutral gas and plasma. The frame 155 can be constructed of any flexiblematerial with at least portions of the frame functioning as springelements to move the thin-wall structure 150 from a collapsedconfiguration (FIG. 1) to an expanded, deployed configuration (FIG. 2)in a patient's uterine cavity. In one embodiment, the frame 155comprises stainless steel elements 158 a, 158 b and 160 a and 160 b thatfunction akin to leaf springs. The frame can be a stainless steel suchas 316 SS, 17A SS, 420 SS, 440 SS or the frame can be a NiTi material.The frame preferably extends along a single plane, yet remains thintransverse to the plane, so that the frame may expand into the uterinecavity. The frame elements can have a thickness ranging from about0.005″ to 0.025″. As can be seen in FIGS. 5 and 6, the proximal ends 162a and 162 b of spring elements 158 a, 158 b are fixed (e.g., by welds164) to the distal end 165 of sleeve member 115. The proximal ends 166 aand 166 b of spring elements 160 a, 160 b are welded to distal portion168 of a secondary translatable sleeve 170 that can be extended frombore 175 in translatable sleeve 115. The secondary translatable sleeve170 is dimensioned for a loose fit in bore 175 to allow gas flows withinbore 175. FIGS. 5 and 6 further illustrate the distal ends 176 a and 176b of spring elements 158 a, 158 b are welded to distal ends 178 a and178 b of spring elements 160 a and 160 b to thus provide a frame 155that can be moved from a linear shape (see FIG. 1) to an expandedtriangular shape (FIGS. 5 and 6).

As will be described further below, the bore 175 in sleeve 115 and bore180 in secondary translatable sleeve 170 function as gas outflow and gasinflow lumens, respectively. It should be appreciated that the gasinflow lumen can comprise any single lumen or plurality of lumens ineither sleeve 115 or sleeve 170 or another sleeve, or other parts of theframe 155 or the at least one gas flow lumen can be formed into a wallof dielectric structure 150. In FIGS. 5, 6 and 7 it can be seen that gasinflows are provided through bore 180 in sleeve 170, and gas outflowsare provided in bore 175 of sleeve 115. However, the inflows andoutflows can be also be reversed between bores 175 and 180 of thevarious sleeves. FIGS. 5 and 6 further show that a rounded bumperelement 185 is provided at the distal end of sleeve 170 to insure thatno sharp edges of the distal end of sleeve 170 can contact the inside ofthe thin dielectric wall 150. In one embodiment, the bumper element 185is silicone, but it could also comprise a rounded metal element. FIGS. 5and 6 also show that a plurality of gas inflow ports 188 can be providedalong a length of in sleeve 170 in chamber 152, as well as a port 190 inthe distal end of sleeve 170 and bumper element 185. The sectional viewof FIG. 7 also shows the gas flow passageways within the interior ofintroducer sleeve 110.

It can be understood from FIGS. 1, 2, 5 and 6 that actuation of firstand second handle portions, 114 a and 114 b, (i) initially causesmovement of the assembly of sleeves 115 and 170 relative to bore 120 ofintroducer sleeve 110, and (ii) secondarily causes extension of sleeve170 from bore 175 in sleeve 115 to expand the frame 155 into thetriangular shape of FIG. 5. The dimensions of the triangular shape aresuited for a patient uterine cavity, and for example can have an axiallength A ranging from 4 to 10 cm and a maximum width B at the distal endranging from about 2 to 5 cm. In one embodiment, the thickness C of thethin-wall structure 150 can be from 1 to 4 mm as determined by thedimensions of spring elements 158 a, 158 b, 160 a and 160 b of frameassembly 155. It should be appreciated that the frame assembly 155 cancomprise round wire elements, flat spring elements, of any suitablemetal or polymer that can provide opening forces to move thin-wallstructure 150 from a collapsed configuration to an expandedconfiguration within the patient uterus. Alternatively, some elements ofthe frame 155 can be spring elements and some elements can be flexiblewithout inherent spring characteristics.

As will be described below, the working end embodiment of FIGS. 2, 5 and6 has a thin-wall structure 150 that is formed of a dielectric materialsuch as silicone that permits capacitive coupling of current to engagedtissue while the frame assembly 155 provides structural support toposition the thin-wall structure 150 against tissue. Further, gasinflows into the interior chamber 152 of the thin-wall structure canassist in supporting the dielectric wall so as to contact endometrialtissue. The dielectric thin-wall structure 150 can be free from fixationto the frame assembly 155, or can be bonded to an outward-facing portionor portions of frame elements 158 a and 158 b. The proximal end 182 ofthin-wall structure 150 is bonded to the exterior of the distal end ofsleeve 115 to thus provide a sealed, fluid-tight interior chamber 152(FIG. 5).

In one embodiment, the gas inflow source 140A comprises one or morecompressed gas cartridges that communicate with flexible conduit 136through plug-in connector 137 and receiving connector 138 in the controlunit 135 (FIGS. 1-2). As can be seen in FIGS. 5-6, the gas inflows fromsource 140A flow through bore 180 in sleeve 170 to open terminations 188and 190 therein to flow into interior chamber 152. A vacuum source 145is connected through conduit 136 and connector 137 to allow circulationof gas flow through the interior chamber 152 of the thin-wall dielectricstructure 150. In FIGS. 5 and 6, it can be seen that gas outflowscommunicate with vacuum source 145 through open end 200 of bore 175 insleeve 115. Referring to FIG. 5, it can be seen that frame elements 158a and 158 b are configured with a plurality of apertures 202 to allowfor gas flows through all interior portions of the frame elements, andthus gas inflows from open terminations 188, 190 in bore 180 are free tocirculated through interior chamber 152 to return to an outflow paththrough open end 200 of bore 175 of sleeve 115. As will be describedbelow (see FIGS. 3-4), the gas inflow source 140A is connected to a gasflow or circulation controller 140B which controls a pressure regulator205 and also controls vacuum source 145 which is adapted for assistingin circulation of the gas. It should be appreciated that the frameelements can be configured with apertures, notched edges or any otherconfigurations that allow for effective circulation of a gas throughinterior chamber 152 of the thin-wall structure 150 between the inflowand outflow passageways.

Now turning to the electrosurgical aspects of the invention, FIGS. 5 and6 illustrate opposing polarity electrodes of the system 100 that areconfigured to convert a flow of neutral gas in chamber 152 into a plasma208 (FIG. 6) and to allow capacitive coupling of current through a wall210 of the thin-wall dielectric structure 150 to endometrial tissue incontact with the wall 210. The electrosurgical methods of capacitivelycoupling RF current across a plasma 208 and dielectric wall 210 aredescribed in U.S. patent application Ser. No. 12/541,043; filed Aug. 13,2009 and U.S. application Ser. No. 12/541,050, referenced above. InFIGS. 5 and 6, the first polarity electrode 215 is within interiorchamber 152 to contact the neutral gas flow and comprises the frameassembly 155 that is fabricated of an electrically conductive stainlesssteel. In another embodiment, the first polarity electrode can be anyelement disposed within the interior chamber 152, or extendable intointerior chamber 152. The first polarity electrode 215 is electricallycoupled to sleeves 115 and 170 which extends through the introducersleeve 110 to handle 106 and conduit 136 and is connected to a firstpole of the RF source energy source 130A and controller 130B. A secondpolarity electrode 220 is external of the internal chamber 152 and inone embodiment the electrode is spaced apart from wall 210 of thethin-wall dielectric structure 150. In one embodiment as depicted inFIGS. 5 and 6, the second polarity electrode 220 comprises a surfaceelement of an expandable balloon member 225 carried by introducer sleeve110. The second polarity electrode 220 is coupled by a lead (not shown)that extends through the introducer sleeve 110 and conduit 136 to asecond pole of the RF source 130A. It should be appreciated that secondpolarity electrode 220 can be positioned on sleeve 110 or can beattached to surface portions of the expandable thin-wall dielectricstructure 150, as will be described below, to provide suitable contactwith body tissue to allow the electrosurgical ablation of the method ofthe invention. The second polarity electrode 220 can comprise a thinconductive metallic film, thin metal wires, a conductive flexiblepolymer or a polymeric positive temperature coefficient material. In oneembodiment depicted in FIGS. 5 and 6, the expandable member 225comprises a thin-wall compliant balloon having a length of about 1 cm to6 cm that can be expanded to seal the cervical canal. The balloon 225can be inflated with a gas or liquid by any inflation source 148, andcan comprise a syringe mechanism controlled manually or by control unit135. The balloon inflation source 148 is in fluid communication with aninflation lumen 228 in introducer sleeve 110 that extends to aninflation chamber of balloon 225 (see FIG. 7).

Referring back to FIG. 1, the control unit 135 can include a display 230and touch screen or other controls 232 for setting and controllingoperational parameters such as treatment time intervals, treatmentalgorithms, gas flows, power levels and the like. Suitable gases for usein the system include argon, other noble gases and mixtures thereof. Inone embodiment, a footswitch 235 is coupled to the control unit 135 foractuating the system.

The box diagrams of FIGS. 3 and 4 schematically depict the system 100,subsystems and components that are configured for an endometrialablation system. In the box diagram of FIG. 3, it can be seen that RFenergy source 130A and circuitry is controlled by a controller 130B. Thesystem can include feedback control systems that include signalsrelating to operating parameters of the plasma in interior chamber 152of the dielectric structure 150. For example, feedback signals can beprovided from at least one temperature sensor 240 in the interiorchamber 152 of the dielectric structure 150, from a pressure sensorwithin, or in communication, with interior chamber 152, and/or from agas flow rate sensor in an inflow or outflow channel of the system. FIG.4 is a schematic block diagram of the flow control components relatingto the flow of gas media through the system 100 and hand-held device105. It can be seen that a pressurized gas source 140A is linked to adownstream pressure regulator 205, an inflow proportional valve 246,flow meter 248 and normally closed solenoid valve 250. The valve 250 isactuated by the system operator which then allows a flow of a neutralgas from gas source 140A to circulate through flexible conduit 136 andthe device 105. The gas outflow side of the system includes a normallyopen solenoid valve 260, outflow proportional valve 262 and flow meter264 that communicate with vacuum pump or source 145. The gas can beexhausted into the environment or into a containment system. Atemperature sensor 270 (e.g., thermocouple) is shown in FIG. 4 that isconfigured for monitoring the temperature of outflow gases. FIG. 4further depicts an optional subsystem 275 which comprises a vacuumsource 280 and solenoid valve 285 coupled to the controller 140B forsuctioning steam from a uterine cavity 302 at an exterior of thedielectric structure 150 during a treatment interval. As can beunderstood from FIG. 4, the flow passageway from the uterine cavity 302can be through bore 120 in sleeve 110 (see FIGS. 2, 6 and 7) or anotherlumen in a wall of sleeve 110 can be provided.

FIGS. 8A-8D schematically illustrate a method of the invention wherein(i) the thin-wall dielectric structure 150 is deployed within a patientuterus and (ii) RF current is applied to a contained neutral gas volumein the interior chamber 152 to contemporaneously create a plasma 208 inthe chamber and capacitively couple current through the thin dielectricwall 210 to apply ablative energy to the endometrial lining toaccomplish global endometrial ablation.

More in particular, FIG. 8A illustrates a patient uterus 300 withuterine cavity 302 surrounded by endometrium 306 and myometrium 310. Theexternal cervical os 312 is the opening of the cervix 314 into thevagina 316. The internal os or opening 320 is a region of the cervicalcanal that opens to the uterine cavity 302. FIG. 8A depicts a first stepof a method of the invention wherein the physician has introduced adistal portion of sleeve 110 into the uterine cavity 302. The physiciangently can advance the sleeve 110 until its distal tip contacts thefundus 324 of the uterus. Prior to insertion of the device, thephysician can optionally introduce a sounding instrument into theuterine cavity to determine uterine dimensions, for example from theinternal os 320 to fundus 324.

FIG. 8B illustrates a subsequent step of a method of the inventionwherein the physician begins to actuate the first and second handleportions, 114 a and 114 b, and the introducer sleeve 110 retracts in theproximal direction to expose the collapsed frame 155 and thin-wallstructure 150 within the uterine cavity 302. The sleeve 110 can beretracted to expose a selected axial length of thin-wall dielectricstructure 150, which can be determined by markings 330 on sleeve 115(see FIG. 1) which indicate the axial travel of sleeve 115 relative tosleeve 170 and thus directly related to the length of deployed thin-wallstructure 150. FIG. 2 depicts the handle portions 114 a and 114 b fullyapproximated thus deploying the thin-wall structure to its maximumlength.

FIG. 8C illustrates several subsequent steps of a method of theinvention. FIG. 8C first depicts the physician continuing to actuate thefirst and second handle portions, 114 a and 114 b, which furtheractuates the frame 155 (see FIGS. 5-6) to expand the frame 155 andthin-wall structure 150 to a deployed triangular shape to contact thepatient's endometrial lining 306. The physician can slightly rotate andmove the expanding dielectric structure 150 back and forth as thestructure is opened to insure it is opened to the desired extent. Inperforming this step, the physician can actuate handle portions, 114 aand 114 b, a selected degree which causes a select length of travel ofsleeve 170 relative to sleeve 115 which in turn opens the frame 155 to aselected degree. The selected actuation of sleeve 170 relative to sleeve115 also controls the length of dielectric structure deployed fromsleeve 110 into the uterine cavity. Thus, the thin-wall structure 150can be deployed in the uterine cavity with a selected length, and thespring force of the elements of frame 155 will open the structure 150 toa selected triangular shape to contact or engage the endometrium 306. Inone embodiment, the expandable thin-wall structure 150 is urged towardand maintained in an open position by the spring force of elements ofthe frame 155. In the embodiment depicted in FIGS. 1 and 2, the handle106 includes a locking mechanism with finger-actuated sliders 332 oneither side of the handle that engage a grip-lock element against anotch in housing 333 coupled to introducer sleeve 110 (FIG. 2) to locksleeves 115 and 170 relative to introducer sleeve 110 to maintain thethin-wall dielectric structure 150 in the selected open position.

FIG. 8C further illustrates the physician expanding the expandableballoon structure 225 from inflation source 148 to thus provide anelongated sealing member to seal the cervix 314 outward from theinternal os 320. Following deployment of the thin-wall structure 150 andballoon 225 in the cervix 314, the system 100 is ready for theapplication of RF energy to ablate endometrial tissue 306. FIG. 8C nextdepicts the actuation of the system 100, for example, by actuatingfootswitch 235, which commences a flow of neutral gas from source 140Ainto the interior chamber 152 of the thin-wall dielectric structure 150.Contemporaneous with, or after a selected delay, the system's actuationdelivers RF energy to the electrode arrangement which includes firstpolarity electrode 215 (+) of frame 155 and the second polarityelectrode 220 (−) which is carried on the surface of expandable balloonmember 225. The delivery of RF energy delivery will instantly convertthe neutral gas in interior chamber 152 into conductive plasma 208 whichin turn results in capacitive coupling of current through the dielectricwall 210 of the thin-wall structure 150 resulting in ohmic heating ofthe engaged tissue. FIG. 8C schematically illustrates the multiplicityof RF current paths 350 between the plasma 208 and the second polarityelectrode 220 through the dielectric wall 210. By this method, it hasbeen found that ablation depths of three mm to six mm or more can beaccomplished very rapidly, for example in 60 seconds to 120 secondsdependent upon the selected voltage and other operating parameters. Inoperation, the voltage at which the neutral gas inflow, such as argon,becomes conductive (i.e., converted in part into a plasma) is dependentupon a number of factors controlled by the controllers 130B and 140B,including the pressure of the neutral gas, the volume of interiorchamber 152, the flow rate of the gas through the chamber 152, thedistance between electrode 210 and interior surfaces of the dielectricwall 210, the dielectric constant of the dielectric wall 210 and theselected voltage applied by the RF source 130, all of which can beoptimized by experimentation. In one embodiment, the gas flow rate canbe in the range of 5 ml/sec to 50 ml/sec. The dielectric wall 210 cancomprise a silicone material having a thickness ranging from a 0.005″ to0.015 and having a relative permittivity in the range of 3 to 4. The gascan be argon supplied in a pressurized cartridge which is commerciallyavailable. Pressure in the interior chamber 152 of dielectric structure150 can be maintained between 14 psia and 15 psia with zero or negativedifferential pressure between gas inflow source 140A and negativepressure or vacuum source 145. The controller is configured to maintainthe pressure in interior chamber in a range that varies by less than 10%or less than 5% from a target pressure. The RF power source 130A canhave a frequency of 450 to 550 KHz, and electrical power can be providedwithin the range of 600 Vrms to about 1200 Vrms and about 0.2 Amps to0.4 Amps and an effective power of 40 W to 100 W. In one method, thecontrol unit 135 can be programmed to delivery RF energy for apreselected time interval, for example, between 60 seconds and 120seconds. One aspect of a treatment method corresponding to the inventionconsists of ablating endometrial tissue with RF energy to elevateendometrial tissue to a temperature greater than 45 degrees Celsius fora time interval sufficient to ablate tissue to a depth of at least 1 mm.Another aspect of the method of endometrial ablation of consists ofapplying radiofrequency energy to elevate endometrial tissue to atemperature greater than 45 degrees Celsius without damaging themyometrium.

FIG. 8D illustrates a final step of the method wherein the physiciandeflates the expandable balloon member 225 and then extends sleeve 110distally by actuating the handles 114 a and 114 b to collapse frame 155and then retracting the assembly from the uterine cavity 302.Alternatively, the deployed working end 122 as shown in FIG. 8C can bewithdrawn in the proximal direction from the uterine cavity wherein theframe 155 and thin-wall structure 150 will collapse as it is pulledthrough the cervix. FIG. 8D shows the completed ablation with theablated endometrial tissue indicated at 360.

In another embodiment, the system can include an electrode arrangementin the handle 106 or within the gas inflow channel to pre-ionize theneutral gas flow before it reaches the interior chamber 152. Forexample, the gas inflow channel can be configured with axially orradially spaced apart opposing polarity electrodes configured to ionizethe gas inflow. Such electrodes would be connected in separate circuitryto an RF source. The first and second electrodes 215 (+) and 220 (−)described above would operate as described above to provide the currentthat is capacitively coupled to tissue through the walls of thedielectric structure 150. In all other respects, the system and methodwould function as described above.

Now turning to FIGS. 9 and 10, an alternate working end 122 withthin-wall dielectric structure 150 is shown. In this embodiment, thethin-wall dielectric structure 150 is similar to that of FIGS. 5 and 6except that the second polarity electrode 220′ that is exterior of theinternal chamber 152 is disposed on a surface portion 370 of thethin-wall dielectric structure 150. In this embodiment, the secondpolarity electrode 220′ comprises a thin-film conductive material, suchas gold, that is bonded to the exterior of thin-wall material 210 alongtwo lateral sides 354 of dielectric structure 150. It should beappreciated that the second polarity electrode can comprise one or moreconductive elements disposed on the exterior of wall material 210, andcan extend axially, or transversely to axis 111 and can be singular ormultiple elements. In one embodiment shown in more detail in FIG. 10,the second polarity electrode 220′ can be fixed on another lubriciouslayer 360, such as a polyimide film, for example KAPTON®. The polyimidetape extends about the lateral sides 354 of the dielectric structure 150and provides protection to the wall 210 when it is advanced from orwithdrawn into bore 120 in sleeve 110. In operation, the RF deliverymethod using the embodiment of FIGS. 9 and 10 is the same as describedabove, with RF current being capacitively coupled from the plasma 208through the wall 210 and endometrial tissue to the second polarityelectrode 220′ to cause the ablation.

FIG. 9 further shows an optional temperature sensor 390, such as athermocouple, carried at an exterior of the dielectric structure 150. Inone method of use, the control unit 135 can acquire temperature feedbacksignals from at least one temperature sensor 390 to modulate orterminate RF energy delivery, or to modulate gas flows within thesystem. In a related method of the invention, the control unit 135 canacquire temperature feedback signals from temperature sensor 240 ininterior chamber 152 (FIG. 6 to modulate or terminate RF energy deliveryor to modulate gas flows within the system.

In another embodiment of the invention, FIGS. 11-14 depict systems andmethods for evaluating the integrity of the uterine cavity which may beperforated or otherwise damaged by the transcervical introduction ofprobes and instruments into a uterine cavity. If the uterine wall isperforated, it would be preferable to defer any ablation treatment untilthe uterine wall is healed. A method of the invention comprisesintroducing transcervically a probe into a patient's uterine cavity,providing a flow of a fluid (e.g., CO2) through the probe into theuterine cavity and monitoring the rate of the flow to characterize theuterine cavity as perforated or non-perforated based on a change in theflow rate. If the flow rate drops to zero or close to zero, thisindicates that the uterine cavity is intact and not perforated. If theflow rate does not drop to zero or close to zero, this indicates that afluid flow is leaking through a perforation in the uterine cavity 302into the uterine cavity or escaping around an occlusion balloon thatoccludes the cervical canal.

In FIG. 11, it can be seen how a pressurized fluid source 405 andcontroller 410 for controlling and monitoring flows is in fluidcommunication with lumen 120 of introducer sleeve 110 (see FIG. 7). Inone embodiment, the fluid source can be a pressurized cartridgecontaining CO2 or another biocompatible gas. In FIG. 12, it can be seenthat fluid source 405 communicates with a flexible conduit 412 that isconnected to a “pig-tail” tubing connector 414 extending outward fromhandle 106 of the hand-held probe. A tubing in the interior of handlecomponent 114 a provides a flow passageway 415 to the lumen 120 in theintroducer sleeve. In another embodiment, the fluid source 405 andflexible conduit 408 can be integrated into conduit 136 of FIG. 1.

In FIG. 11, it can be seen that the flow of fluid is introduced into theuterine cavity 302 after the balloon 225 in the cervical canal has beeninflated and after the working end and dielectric structure 150 has beenexpanded into its triangular shape to occupy the uterine cavity. Thus,the CO2 gas flows around the exterior surfaces of expanded dielectricstructure 150 to fill the uterine cavity. Alternatively, the flow of CO2can be provided after the balloon 225 in the cervical canal is inflatedbut before the dielectric structure 150 is expanded.

FIG. 13 is a block diagram that schematically depicts the components ofsubsystem 420 that provides the flow of CO2 to and through the hand-heldprobe 105. It can be seen that pressurized fluid source 405 communicateswith a downstream pressure regulator 422, a proportional valve 424, flowmeter 440, normally closed solenoid valve 450 and one-way valve 452. Thevalve 450 upon actuation by the system operator allows a flow of CO2 gasfrom source 405 at a predetermined flow rate and pressure through thesubsystem and into the uterine cavity 302.

In one embodiment of the method of operation, the physician actuates thesystem and electronically opens valve 450 which can provide a CO2 flowthrough the system. The controller 410 monitors the flow meter or sensor440 over an interval that can range from 1 second to 60 seconds, or 5second to 30 seconds to determine the change in the rate of flow and/ora change in the rate of flow. In an embodiment, the flow sensorcomprises a Honeywell AWM5000 Series Mass Airflow Sensor, for exampleModel AWM5101, that measure flows in units of mass flow. In oneembodiment, the initial flow rate is between 0.05 slpm (standard litersper minute) and 2.0 slpm, or between 0.1 slpm and 0.2 slpm. Thecontroller 410 includes a microprocessor or programmable logic devicethat provides a feedback signal from the flow sensors indicating either(i) that the flow rate has dropped to zero or close to zero to thuscharacterize the uterine cavity as non-perforated, or (ii) that the flowrate has not dropped to a predetermined threshold level within apredetermined time interval to thus characterize the uterine cavity asperforated or that there is a failure in occlusion balloon 225 or itsdeployment so that the cervical canal is not occluded. In oneembodiment, the threshold level is 0.05 slpm for characterizing theuterine cavity as non-perforated. In this embodiment, the controllerprovides a signal indicating a non-perforated uterine cavity if the flowdrops below 0.05 slpm between the fifth second of the flow and the flowtime-out, which can be, for example, 30 seconds.

FIG. 14 depicts aspects of an algorithm used by controller 410 toaccomplish a uterine cavity integrity check, with the first stepcomprising actuating a footswitch or hand switch. Upon actuation, atimer is initialized for 1 to 5 seconds to determine that a fluid source405 is capable of providing a fluid flow, which can be checked by apressure sensor between the source 405 and pressure regulator 422. If noflow is detected, an error signal is provided, such as a visual displaysignal on the control unit 135 (FIG. 1).

As can be understood from FIG. 14, after the fluid source 405 ischecked, the controller opens the supply solenoid valve 450 and a timeris initialized for a 1 to 5 second test interval to insure fluid flowsthrough the subsystem 420 of FIG. 13, with either or both a flow meter440 or a pressure sensor. At the same time as valve 450 is opened, atimer is initialized for cavity integrity test interval of 30 seconds.The controller 410 monitors the flow meter 440 and provides a signalcharacterizing the uterine cavity as non-perforated if, at any timeafter the initial 5 second check interval and before the end of thetimed-out period (e.g., the 30 second time-out), the flow rate dropsbelow a threshold minimum rate, in one embodiment, to below 0.05 slpm.If the interval times out after 30 seconds and the flow rate does notdrop below this threshold, then a signal is generated that characterizesthat the uterine cavity is perforated. This signal also can indicate afailure of the occlusion balloon 225.

Referring to FIG. 14, in one embodiment, in response or otherwise as aresult of the signal that the uterine cavity is not perforated, thecontroller 410 can automatically enable and activate the RF ablationsystem described above to perform an ablation procedure. The controller410 can provide a time interval from 1 to 15 seconds to allow CO2 gas tovent from the uterine cavity 302 before activating RF energy delivery.In another embodiment, the endometrial ablation system may include theoptional subsystem 275 for exhausting fluids or gas from the uterinecavity during an ablation treatment (see FIG. 4 and accompanying text).This subsystem 275 can be actuated to exhaust CO2 from the uterinecavity 302 which include opening solenoid valve 285 shown in FIG. 4.

The system can further include an override to repeat the cavityintegrity check, for example, after evaluation and re-deployment of theocclusion balloon 225.

FIGS. 15 and 16 represent another system and method for characterizingthe uterine cavity as being non-perforated so as to safely permit anablation procedure. This system and method utilizes variations in thealgorithms that introduce a gas media fluid into the uterine cavity andthereafter measure the changes in flow rates in the gas media. Thesystem again is configured to introduce a gas into the uterine cavityafter deployment and expansion of an ablation device in the cavity. Ifthe flow rate drops of the gas to approximately zero, this indicatesthat the uterine cavity is intact and not perforated. In the event, theflow rate of the gas does not drop, there is likely a gas flow escapingfrom the uterine cavity 302 through a perforation in the uterine wall.

FIG. 15 schematically illustrates three different conditions that mayoccur when operating the system, which indicate whether the system isfunctioning properly, and whether the uterine wall is non-perforated orperforated. In FIG. 15, the vertical axis indicates a gas flow ratemeasure in slpm (standard liters per minute), and the horizontal axisrepresents time in seconds. In one system variation, a gas source 405such as a pressurized cartridge containing CO₂ is controlled by acontroller 410, and the gas is introduced into the uterine cavitythrough a passageway in the device introducer sleeve 110 as describedabove (FIGS. 11-13). The controller 410 and flowmeter monitors flowsfrom the device into the uterine cavity (FIG. 13). The initial flow ratecan be in the range of 0.010 slpm to 0.20 slpm. In one aspect of theinvention, a minimum flow rate has been found to be important as asystem diagnostic check to insure gas flow is reaching the uterinecavity. Thus, FIG. 15 illustrates gas flow rate curve in a “condition 1”that may occur when the system fails in delivering gas through thepassageways of the system. In one variation, the “condition 1” will berepresented by a flow rate over time wherein the flow rate does notachieve a minimum threshold flow rate, which can be from 0.010 slpm to0.050 slpm over a predetermined time interval. In one variation, theminimum flow rate is 0.035 slpm. The time interval can be from 1 secondto 15 seconds. This “condition 1” as in FIG. 15 could occur, forexample, if the gas supply tubing within the device were kinked orpinched which would then prevent gas flow through the system and intothe uterine cavity. In a related variation that indicates systemfailure, a controller algorithm can calculate the volume of gasdelivered, and if the volume is less than a threshold volume, then asystem failure or fault can be determined. The gas volume V₁ isrepresented by the “area under the curve” in FIG. 15, which is afunction of flow rate and time.

FIG. 15 further illustrates a flow rate curve in a “condition 2” whichcorresponds to an intact, non-perforated uterine cavity. As can beunderstood from a practical perspective, a gas flow into an intactuterine cavity at a set pressure from a low pressure source, for examplewithin a range of 0.025 psi to 1.0 psi, would provide an increasing flowrate into the cavity until the cavity was filled with gas, andthereafter the flow rate would diminish to a very low or zero flow rate.Such a “condition 2” flow rate curve as in FIG. 15 further assumes thatthere is an adequate sealing mechanism in the cervical canal. Thus, ifcontroller obtains flow rate data from the flowmeter indicating“condition 2”, then the patient's uterus is non-perforated and issuitable for an ablation. In operation, the controller can look atvarious specific aspects and parameters of the flow rate curve of“condition 2” in FIG. 15 to determine that the uterine cavity integritytest has passed, wherein such parameters can comprise any singleparameter or a combination of the following parameters: (i) the flowrate falling below a threshold rate, for example between 0.010-0.10slpm; (ii) a change in rate of flow; (iii) a peak flow rate; (iii) thetotal gas volume V₂ delivered; (iv) an actual flow rate at a point intime compared to a peak flow rate; (v) a derivative of flow rate at apoint in time, and (vi) any of the preceding parameters combined with apredetermined time interval. In one embodiment, a constant pressure(0.85 psi) gas is introduced and a minimum threshold flow is set at0.035 slpm. A peak flow is calculated after a time interval of 2 to 15seconds, and thereafter it is determined if the flow rate diminished byat least 10%, 20%, 30%, 40% or 50% over a time interval of less than 30seconds.

FIG. 15 next illustrates a flow rate curve in “condition 3” whichrepresents a gas flow when there is a perforated wall in a uterinecavity, which would allow the gas to escape into the abdominal cavity.In FIG. 15, a gas flow at a constant pressure is shown ramping up inflow rate until it levels off and may decline but not the rate ofdecline to may not go below a threshold value or may not decline asignificant amount relative to a peak flow rate. Such a flow rate curveover time would indicate that the gas is leaking from the uterinecavity.

Now turning to FIG. 16, an algorithm diagram is shown that describe onevariation in a method of operating a uterine cavity integrity test basedon measuring gas flow rates over a selected time interval. At the top ofthe diagram, the physician actuates the system in which a valve 450 isopened to provide a CO₂ flow through the system (FIG. 14). Thecontroller 410 provides a flow at a pressure, for example 0.85 psi. Theactuation of the system also starts a timer wherein a first interval is30 seconds or less. Over this 30-second interval, the controller recordsthe peak flow rate which typically can occur within 2 to 10 seconds,then monitors the flow rate over the remainder of the 30 second intervaland determined whether the flow rate drops 20% or more from the peakflow rate. Then, the controller additionally monitors whether the flowrate falls below a threshold value, for example 0.035 slpm. If these twoconditions are met, the test indicates that there is no leakage of gasmedia from the uterine cavity. If the flow rates does not drop 20% fromits peak with 30 seconds together with flow being below threshold value,then the test fails indicating a leak of gas from the uterine cavity.Thereafter, the diagram in FIG. 16, indicates one additional test whichconsists of calculating the volume of gas delivered and comparing thevolume to the maximum volume within a kinked gas delivery line. If thedelivered gas volume is less than the capacity of the gas delivery line,then the test fails and the signal on the controller can indicate thistype of test failure. If the delivered gas volume is greater than thecapacity of a gas delivery line, then the test passes. In one variationof the controller algorithm can then automatically actuate the deliveryof RF energy in an ablation cycle. Alternatively, the controller canprovide a signal that the test has passed, and the physician canmanually actuate the RF ablation system.

FIG. 17 schematically illustrates another system and method forcharacterizing integrity of the walls of a uterine cavity. As can beseen in FIG. 17. an introducer sleeve 510 carrying an expandable workingend 520 in deployed in the uterine cavity 302. The working end includesa balloon-like member 522 with a fluid-tight interior chamber 524. Inone embodiment, the working end 510 is expanded laterally by frameelements 526 a and 526 b, which is similar to previously describedembodiments. In addition, a pressurized gas source 540 is actuated toprovide an inflation gas thru interior sleeve 542 and ports 544 thereinthat further expands and opens the working end 520 transverse to openingforces applied by frame elements 526 a and 526 b. The inflation gas cancomprise an argon gas that later is converted to a plasma as describedpreviously. The inflation gas can pressurize the working end to aselected pressure ranging from 0.10 psi to 10 psi. In one variation, thepressure can be 0.50 psi.

As can be seen in FIG. 17, an expandable member 548 or balloon isexpanded to prevent any gas flow outwardly through the bore 550 inintroducer sleeve 510. Thereafter, a gas inflow system 410 similar tothat of FIG. 13 is utilized to flow a gas source, such as CO₂ into theuterine cavity 302 (FIG. 17). In FIG. 17, the gas inflow is indicated byarrows 555 which can comprise an inflow at a predetermined pressurethrough passageway 558 as described above, and in one variation can be0.85 psi. The test for uterine cavity integrity then can monitor one ormore gas leakage parameters relating to the inflation gas in theinterior chamber 524 of the working end 520. For example, the flow intothe uterine cavity 302 will cause an outflow of gas from the interiorchamber 524 through passageway 558 which can be measure by a flow meter,or the volume of gas outflow can be measured or the change in gaspressure can be measured. If there is no leak in the uterine cavity, theparameter of the inflation can in the interior chamber 524 will reach anequilibrium in relation to the CO₂ inflow into the cavity. If theinflation gas parameter does not reach an equilibrium, then the changein parameter (flow, volume or pressure) will indicate a leakage of gasfrom the uterine cavity through a perforation. In general, a method ofcharacterizing the integrity of a patient's uterus comprises positioninga probe working end is a patient's uterine cavity, the working endcomprising an inflated resilient structure, introducing a flow of a gasthrough the probe into a uterine cavity exterior about the exterior ofthe working end, and measuring a gas flow, gas volume or gas pressureparameter of the inflation media in the inflated resilient structure inresponse to the gas flow into the uterine cavity.

FIGS. 18A-20B illustrates other methods of characterizing and/ortreating a patient's uterus, which include a multi-stage test foruterine wall integrity which enhances safety. In general, a multi-stagetest corresponding to the invention comprises positioning a probeworking end in a patient's uterine cavity, introducing a first fluidinto the expandable working end, introducing a second fluid into theuterine cavity exterior of the working end, and performing first andsecond monitoring tests relating to parameters of the first and secondfluids to thereby characterize a uterine wall. Thereafter, the physiciancan actuate an ablation mechanism carried by the working end uponcharacterization of the uterine wall as intact or non-perforated. In oneembodiment, the step of actuating the ablation mechanism is automated bya controller upon a signal from at least one sensor that uterine cavityis intact.

FIGS. 18A and 18B illustrate in more detail a two-stage method fortesting the integrity of a uterine wall or uterine cavity. In FIG. 18A,it can be seen that the elongate introducer sleeve 510 carrying anexpandable working end 520 is properly deployed in the uterine cavity302. The working end again includes an expandable thin-wall resilientmember such as a dielectric member 522 with a fluid-tight interiorchamber 524. The cervical seal 604 is positioned in the cervical canalwith a cervical cuff 606 expanded and the dielectric structure 522 isexpanded as described previously. FIG. 18A further illustrates an inflowof CO₂ gas from source 420 into the uterine cavity 302 through sleeve510 about the exterior of the dielectric structure 522. Thus, the firsttest stage illustrated in FIG. 18A consists of the cavity integrity testdescribed above in conjunction with FIGS. 15-16 wherein the CO₂ inflowis monitored for a predetermined decay in the CO₂ flow rate to determinewhether a perforation in the uterine cavity may exist.

Now turning to FIG. 18B, a second stage of the test is illustrated. Inthe second stage, Argon gas from source 610 is controlled by thecontroller 615 to provide a flow into the interior chamber 524 of thedielectric structure 522. As can be understood in FIG. 18B, anysignificant or slight expansion of the dielectric surface 612 (seearrows in FIG. 18B) by the Argon inflation in the dielectric structure522 will impinge on CO₂ flows about the exterior of the dielectricstructure 522. Thus, the second stage of the cavity integrity testincludes monitoring the flow rate of the CO₂ with a flowmeter 625 forchanges that are indicative of expansion of the dielectric structurewall which impinges on the CO₂ flow rate. In FIG. 18B, it can beunderstood that when the dielectric structure 522 is fully expandedwithin the uterine cavity, there remains very little space between thedielectric wall and the uterine wall for CO₂ to flow. In other words,any expansion of the dielectric structure 522 will result in asignificant change in flow of the CO₂. In some cases, the flow metercoupled to the CO₂ inflow lumen can detect CO₂ outflow. In the event thesystem is configured for a circulating flow of CO₂ into and out of thedielectric structure, a flowmeter 625 can detect a change in the flowrate caused by the dielectric structure impinging on such a flow rate.The second stage of the test illustrated FIG. 18B this can confirmdielectric structure 522 is properly deployed and expanded cavity 302.

FIG. 19 is a box diagram that indicates one [embodiment] mentioned andthe steps involved in the second stage of the two-stage cavity integritytest. In one embodiment, CO₂ flow to the exterior of the dielectricstructure is activated at T=zero. At T=2 seconds, the controller 615activates the Argon positive pressure source at a flow rate of 0.8 SLPMusing a flow control loop. Pressure for the Argon in the interiorchamber the dielectric structure can be set at 0.5 psig using theproportional valve in the return line and a pressure sensing mechanism.Thereafter, the controller monitors CO₂ flows to determine whether theArgon flow into the interior dielectric structure impinges on CO₂ flows.In one example, after 2 seconds, a significant change the CO₂ flows willindicate that the dielectric structure is substantially positioned inthe uterine cavity 302 and is properly expanded. In this stage of thetest, if the controller 615 does not receive a signal indicating achange in CO₂ flows, this indicates that the dielectric structure 522 itis not deployed substantially within the uterine cavity 302 and theworking end may have penetrated the wall of the uterine cavity to someextent and further is plugging the perforation thus preventing any leak.

FIGS. 20A and 20B illustrate the two-stage cavity integrity test in asituation wherein the dielectric structure 522 has at least partiallyperforated the uterine wall, unlike the proper working end deployment asdepicted in FIGS. 18A-18B. As can be seen in FIG. 20A, the dielectricstructure 522 has penetrated the fundus 618 and is only partiallyopened. Such a uterine wall perforation could occur in the fundus 618 orelsewhere in the uterine wall in an asymmetrically shaped uterinecavity. Such a perforation could be caused by the working end of theprobe itself, or the perforation could be caused by a soundinginstrument that is used in a preliminary step in which the physicianmeasures the length of the uterine cavity.

FIG. 20A illustrates the first stage of the two-part test wherein CO₂flows from the CO₂ source 620 into the uterine cavity 302 through theintroducer sleeve 510 and about the exterior of the dielectric structure522. It can be seen that the gas flows may not penetrate the perforationsince the perforation may be effectively plugged by the silicone surfaceof the dielectric structure 522. Thus, FIG. 20A illustrates a conditionwherein the first stage of the test which monitors only CO₂ flow wouldindicate that the cavity has no perforations, when in fact there is aperforation that is masked by the dielectric structure 522 plugging theperforation.

FIG. 20B illustrates the second stage of the two-stage test whereinArgon is introduced into the interior chamber 524 the dielectricstructure 522. In FIG. 20B, it can be seen that the expansion of thedielectric wall is limited as indicated by the arrows since the distalportion 632 portion of the dielectric structure 522 is embedded and notexpandable within the perforation in the uterine fundus. In this case,the introduction of Argon gas into the dielectric structure detects theperforation in the uterine wall which otherwise would not have beendetected by the first stage of the test. In the situation indicated inFIG. 20B, the flow of Argon would be constrained and there would belittle fluctuation in the CO₂ flow rate—thus indicating that thedielectric structure 522 is not properly expanded and likely is disposedwithin a perforated uterine wall.

FIG. 21 illustrates another variation in the second stage of thetwo-stage cavity integrity test that records and compares alternativeparameters of fluid flows within the uterine cavity 302 and in theinterior chamber 524 of dielectric structure 522. This method variationcompares a change in a gas pressure parameter in Argon gas in thedielectric structure 522 over a time interval of several seconds. First,the controller 615 turns on the Argon gas for 2 seconds at a flow rateof 0.8 SLPM using a flow control loop. The controller further sets thedielectric pressure at 0.5 psig. Next, the controller turns on the CO₂flow to the uterine cavity exterior of the dielectric structure. Thecontroller 615 is configured to insure that the CO₂ flow is sufficientlylow to maintain a seal between the cervical cuff 606 and the interior osof the cervical canal. If CO₂ flow were higher than a predeterminedlimit, the uterine integrity test could fail because of CO₂ leakagearound the cervical cuff.

Next, the controller 615 turns off the Argon flow by closing a valve inthe Argon flow system. Thus, the dielectric is maintained at 0.5 psig.After 2 seconds, the Argon pressure (P₁) is recorded with CO₂ flowingabout the exterior of the dielectric. Next, the CO₂ flow is turned offand the Argon pressure is recorded after one second, which is Argonpressure P₂ with no CO₂ flowing about the exterior of the dielectric.The final step then compares P₁ and P₂. If P₁ is greater than P₂ (plus apredetermined margin) the cavity integrity test is successful andcharacterizes the uterine wall as non-perforated. If P₁ is not greaterthan P₂ (plus the predetermined margin), the cavity integrity test is nosuccessful and a perforation detected message is displayed by thecontroller.

In general, a method corresponding to the invention for characterizing apatient's uterus, comprises positioning an expandable structure in apatient's uterine cavity, introducing a gas into the uterine cavityexterior of expandable structure, introducing a gas into the expandablestructure, and monitoring a gas parameter in the gas both interior andexterior of the expandable structure to thereby characterize the uterinecavity as either perforated or non-perforated. The gas introduced at theexterior of the expandable structure can be CO₂. The gas introduced intothe interior of the expandable structure can be a neutral gas. Themethod can monitor any gas parameter which is useful for leak detection.In one variation, the leak detecting parameter is a gas flow rate. Inanother variation, the leak detecting parameter is a gas pressure. Inanother variation, the leak detecting parameter is gas volume.

In general, the method can include monitoring the gas parameterscontemporaneously and/or sequentially. The monitoring step can monitorgas parameters first in the uterine cavity and then subsequently in theexpandable structure, or vice versa. Further, the method can monitor agas parameter in the uterine cavity at least twice and can monitor a gasparameter in the expandable structure at least twice.

Now turning to FIGS. 22A-22B, another variation of system and method foroperating a uterine cavity integrity test is based on measuring a gasinflow rate into the uterine cavity. FIG. 22A depicts an expandableworking end or structure 700 that is operatively coupled to subsystemsdescribed previously, i.e., a pressurized CO₂ flow source 705 forproviding gas inflow into the uterine cavity 302, a controller 710 forcontrolling gas inflows, and a flowmeter 715 operatively coupled to thecontroller for measuring the rate of gas inflows. In this embodiment, anadditional negative pressure source 720 is provided for applyingnegative pressure to an interior chamber 722 of the thin-wall dielectricsheath 725 that again comprises a working end 700 similar to embodimentsdescribed above. The working end of FIGS. 22A-22B again includes anexpandable frame 726 as in the FIGS. 5-6 that is expandable withininterior chamber 722 of thin-wall dielectric sheath 725. In FIG. 22A,the introducer sleeve 510 carrying the expandable working end 700 isproperly deployed in uterine cavity 302. The cervical seal 604 ispositioned in the cervical canal with a cervical cuff 606 expanded andthe dielectric sheath 725 is expanded as described previously. FIG. 22Afurther illustrates an inflow of CO₂ gas from source 705 into theuterine cavity 302 through sleeve 510 about the exterior of thedielectric structure or sheath 725.

The test depicted in FIG. 22A is similar to the cavity integrity testdescribed above in conjunction with FIGS. 15-16 wherein the CO₂ inflowis monitored for a predetermined decay in the CO₂ flow rate to determinewhether a perforation in the uterine cavity may exist. The variation ofthe test in FIG. 22A adds an additional intermediate step. Prior toinitiating a CO₂ inflow, the controller 715 and test algorithm isconfigured to actuate negative pressure source 720 to thereby suctiongas from the interior chamber 722 of dielectric sheath 725 to suctionthe thin-wall sheath against the interior frame 726. The negativepressure can be from 5 to 10 psi below ambient, or any similarachievable negative pressure which is maintained for the subsequent stepof inflowing CO₂ into the uterine cavity. FIG. 22A, the sheath region730 indicates walls that are suctioned and collapsed toward one anotherseparated only by the interior frame 726. As can be seen in FIG. 22A,the expandable dielectric sheath 725 and frame 726 is properly expandedwithin the uterine cavity 302 and no perforations are shown. In thiscase, referring back to FIGS. 15 and 16 and the accompanying text, thecavity integrity test would provide an inflow of CO₂ at an initial orfirst flow rate of at least 0.040 slpm (if measured in free air). TheCO₂ inflow would continue for up to 30 seconds or until the flow ratedecayed and remained below a second flow rate for a selected timeinterval of at least 1 second, at least 2 seconds, 5 at least seconds,or at least 10 seconds. In one system and method, the second flow rateis less than the first flow rate and less than 0.050 slpm. In onemethod, the initial or first flow rate (in free air) is 0.070 slpm, theinflow is continued for 30 seconds or until the flow rate decays to0.034 slpm and then the flow rate continuously remains below 0.034 slpmfor 5 seconds. If the previous conditions are met, then the controller710 would display a message and signal that the test indicates that theuterine cavity is non-perforated. In one embodiment, the controller 710and operational algorithm is configured to automatically activate the RFsource to thereby initiate the endometrial ablation treatment. Inanother embodiment, the controller 710 is configured only to enable theRF source and thereafter the physician can manually activate the RFsource to initiate the ablation procedure.

The utility of the above-described cavity integrity test can beunderstood with reference to FIG. 22B, which depicts the working end 700and dielectric sheath 725 within an exemplary perforation 736 in theuterine wall tissue 738. In FIG. 22B, it can be seen that the sheath 715and interior frame 726 have a partially expanded configuration andextending through a perforation that could have been created by a‘sound’ instrument used to measure dimensions of the uterine cavity.FIG. 22B depicts the controller 715 and algorithm after actuation of thecavity integrity test wherein negative pressure source 720 is actuatedto suction gas from interior chamber 722 of dielectric sheath 725. InFIGS. 22B and 23, it can be seen that thin-wall dielectric sheath 725 isunder negative with sheath wall regions 730′ suctioned and collapsedtoward one another and separated only by interior frame 726. FIG. 23 isan enlarged cut-away view of the sheath 725 in the perforation of FIG.22B and shows best how the suctioned down sheath region 730′ leaves atrough 740 between tissue 738 (hatched region) and the sheath 725through which inflowing CO₂ can escape from the uterine cavity 302through the perforation 736 in tissue 738. Under the previous testparameters, the CO₂ flow would escape the uterine cavity 302 and thetest algorithm would find that there was no flow decay over a selectedtime interval (e.g., 5 to 30 seconds). Thus, the controller 715 woulddisplay a message that a perforation existed and the RF source would bedisabled. In contrast, if the sheath 725 was not under negativepressure, it can be understood that the sheath 725 and interior frame726 could plug the perforation and thus prevent CO₂ escape—which wouldthen result in flow decay which in turn would mask the perforation 736.

The cavity integrity test described above with reference to FIGS.22A-22B can be used as a single stage test or it can be usedsequentially with the earlier described test of FIGS. 15-16. Such atwo-stage test could add an additional level of safety to cavityintegrity testing.

FIG. 24 illustrates a two stage cavity integrity test wherein the firststage is similar to that of FIGS. 15-16 and the second stage is the testdescribed with reference to FIGS. 22A-22B. More in particular, gasinflow into the interior chamber 722 of the dielectric 725 is provideduntil the pressure reaches a predetermined level which in one algorithmis 0.50 psi. Thereafter, CO₂ inflows into the uterine cavity areinitiated as described above and then flow decay is monitored until flowdiminished to less that a predetermined level which in on algorithm is0.034 slpm. If this first aspect of the test is achieved in less that 10seconds, 30 seconds or 60 seconds, then the second stage of the test isas described with reference to FIGS. 22A-23 wherein the interior chamber722 of the dielectric 725 is suctioned down against frame 726 and theflow decay test is repeated over another predetermined time intervalwhich can be from 10 to 60 seconds. In all other respects, thetwo-stages test depicted in FIG. 24 corresponds to the stages describedindividually above.

Although particular embodiments of the present invention have beendescribed above in detail, it will be understood that this descriptionis merely for purposes of illustration and the above description of theinvention is not exhaustive. Specific features of the invention areshown in some drawings and not in others, and this is for convenienceonly and any feature may be combined with another in accordance with theinvention. A number of variations and alternatives will be apparent toone having ordinary skills in the art. Such alternatives and variationsare intended to be included within the scope of the claims. Particularfeatures that are presented in dependent claims can be combined and fallwithin the scope of the invention. The invention also encompassesembodiments as if dependent claims were alternatively written in amultiple dependent claim format with reference to other independentclaims.

Other variations are within the spirit of the present invention. Thus,while the invention is susceptible to various modifications andalternative constructions, certain illustrated embodiments thereof areshown in the drawings and have been described above in detail. It shouldbe understood, however, that there is no intention to limit theinvention to the specific form or forms disclosed, but on the contrary,the intention is to cover all modifications, alternative constructions,and equivalents falling within the spirit and scope of the invention, asdefined in the appended claims.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. The term “connected” is to beconstrued as partly or wholly contained within, attached to, or joinedtogether, even if there is something intervening. Recitation of rangesof values herein are merely intended to serve as a shorthand method ofreferring individually to each separate value falling within the range,unless otherwise indicated herein, and each separate value isincorporated into the specification as if it were individually recitedherein. All methods described herein can be performed in any suitableorder unless otherwise indicated herein or otherwise clearlycontradicted by context. The use of any and all examples, or exemplarylanguage (e.g., “such as”) provided herein, is intended merely to betterilluminate embodiments of the invention and does not pose a limitationon the scope of the invention unless otherwise claimed. No language inthe specification should be construed as indicating any non-claimedelement as essential to the practice of the invention.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventors expect skilled artisans to employ such variations asappropriate, and the inventors intend for the invention to be practicedotherwise than as specifically described herein. Accordingly, thisinvention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference were individually and specifically indicatedto be incorporated by reference and were set forth in its entiretyherein.

What is claimed is:
 1. A method of characterizing a patient's uterus,the method comprising: positioning an expandable structure in apatient's uterine cavity, the expandable structure comprising a portionof an energy application system for delivering ablation energy touterine tissue; expanding the expandable structure within the uterinecavity; introducing a gas into the uterine cavity exterior of expandablestructure expanded within the uterine cavity; introducing a gas into theexpandable structure as the expandable structure expands; monitoring aflow rate of the gas introduced into the expandable structure as theexpandable structure expands; monitoring a flow rate of the gasintroduced into the uterine cavity exterior of the expandable structureas the expandable structure expands; and determining whether the uterinecavity is perforated or non-perforated based on the monitored flow rateof the gas introduced into the expandable structure and the monitoredflow rate of the gas introduced into the uterine cavity exterior of theexpandable structure, wherein the uterine cavity is determined asperforated if the flow rate of the gas introduced into the expandablestructure impinges the flow rate of the gas introduced into the uterinecavity exterior of the expandable structure.
 2. The method of claim 1wherein the positioning step comprises transcervically introducing aprobe into the uterine cavity, the probe carrying the expandablestructure.
 3. The method of claim 1 wherein the gas introduced into theuterine cavity is CO2.
 4. The method of claim 1 wherein the gasintroduced into the expandable structure is Argon.
 5. The method ofclaim 1 wherein the flow rate of the gas introduced into the uterinecavity impinges the flow rate of the gas introduced into the uterinecavity exterior of the expandable structure if the flow rate of the gasintroduced into the uterine cavity changes during the introduction ofthe gas into the expandable structure.
 6. The method of claim 1 whereinthe flow rates of the gas introduced into the expandable structure andthe introduced into the uterine cavity exterior of the expandablestructure are monitored contemporaneously.
 7. The method of claim 1wherein the flow rates of the gas introduced into the expandablestructure and the introduced into the uterine cavity exterior of theexpandable structure are monitored sequentially.
 8. The method of claim7 including the flow rate of the gas introduced into the uterine cavityis monitored first and then the flow rate of the gas introduced into theexpandable structure is monitored.
 9. The method of claim 8, wherein theflow rate of the gas introduced into the expandable structure ismonitored 2 seconds after the flow rate of the gas introduced into theuterine cavity is monitored.
 10. The method of claim 7 including theflow rate of the gas introduced into the expandable structure ismonitored first and then the flow rate of the gas introduced intouterine cavity is monitored.
 11. The method of claim 1 wherein the flowrate of the gas introduced into the uterine cavity is monitored at leasttwice.
 12. The method of claim 1 wherein the flow rate of the gasintroduced into the expandable structure is monitored at least twice.13. The method of claim 1 wherein the gas is introduced into theexpandable structure at a flow rate of 0.8 SLPM.
 14. The method of claim1 wherein the expanding of the expandable structure within the uterinecavity comprises expanding a frame in an interior chamber of theexpandable structure.
 15. The method of claim 14 further comprisingapplying a negative pressure to an interior chamber of the expandablestructure to suction an expandable thin wall sheath against the frame.